Showing papers by "Richard J Goldstein published in 2008"
TL;DR: In this article, the Nusselt numbers from heat transfer experiments employing a constant temperature boundary condition are compared to the Sherwood number from mass transfer experiments using a constant concentration boundary condition.
33 citations
TL;DR: In this paper, the authors investigated the mechanism of energy separation in the vortex field behind an adiabatic circular cylinder and measured velocity and recovery temperature data are expressed in nondimensional form as an energy separation factor.
Abstract: Energy separation is a spontaneous redistribution of total energy (enthalpy) in a fluid without external work or heat flow, resulting in some portion of fluid having higher total energy (enthalpy) and another portion having lower energy (enthalpy) than the surrounding fluid. The present study investigates the mechanism of energy separation in the vortex field behind an adiabatic circular cylinder. Time-averaged velocity and temperature measurements are carried out in the wake of a cylinder in a cross flow of air. The measurements are performed at downstream locations of three, five, seven, and ten diameters, for a Reynolds number, based on upstream velocity and cylinder diameter, of 9.2×10 4 and freestream Mach number of 0.22. The measured velocity and recovery temperature data are expressed in nondimensional form as an energy separation factor. The distribution of energy separation factor indicates that the main cause of energy separation is the periodic vortex flow in the wake. The vortex strength and the separation effect decrease as the flow moves downstream. However, energy separation is observed even ten diameters downstream.
16 citations
01 Jan 2008
TL;DR: In this paper, a parametric study is conducted to investigate the effect of wall shear on a two-dimensional turbulent boundary layer, where the velocity and mass transfer experiments have been performed for four surface-to-freestream velocity ratios (0, 038, 052, 065) with a Reynolds number based on the momentum thickness between 770 and 1776.
Abstract: A parametric study is conducted to investigate the effect of wall shear on a two-dimensional turbulent boundary layer The shear is imparted by a moving belt, flush with the wall, translating in the flow direction Velocity and mass transfer experiments have been performed for four surface-to-freestream velocity ratios (0, 038, 052, 065) with a Reynolds number based on the momentum thickness between 770 and 1776 The velocity data indicate that the location of the ‘virtual origin’ of the turbulent boundary layer ‘moves’ downstream towards the trailing edge of the belt with increasing surface velocity The highest velocity ratio represents a case which is responsible for the removal of the inner region of the boundary layer Mass transfer measurements downstream of the belt show the presence of a local minimum in the variation of the Stanton vs Reynolds number for the highest velocity ratio Downstream of this minimum, approximately 1 cm from the leading edge of the mass transfer plate, the characteristics of the turbulent boundary layer are restored and the data fall back on the empirical variation of the Stanton number with Reynolds numberCopyright © 2008 by ASME
2 citations